About this 3D model

I need to build a stackable planetary gear for a project of mine. Little by little I'll complete this ;) edit: you can find a video here https://www.youtube.com/watch?v=CbXVSoI79gw Sry, it's in italian. The gear ration of each stage it's about 3.5 and 3.14, for a final ratio of 10.99:1